They both have their strengths.
I find that DC has better story telling overall, but I love strong psychological tones and they are evident in most of DC's work.
Marvel has some really cool characters, especially their villains. The only DC villain I can put in remotely the same league as Magneto would be Joker.
Magneto is a bad ass.
Marvel created their characters with more limited abilites, where as DC created characters with more god like powers/less weaknesses but more situations where their powers cannot save them.
DC's Philosophy - Strong as hell heroes, STRONGER villains.
Marvels Philosophy - Flawed Heroes, Insane Villains.